An increasing number of automobiles and other vehicles are including devices such as navigation systems, which use satellite or GPS information to track and provide navigation information to the driver. Some of these systems also provide additional “real-time” information, such as traffic information or gas price information, which is added on top of the geographic data displayed to the driver. While some systems utilize satellite radio signals, others utilize common FM frequencies. When common FM frequencies are used, a common quarter-wave antenna typically is needed to pick up the signal with acceptable strength. Since an FM frequency of about 100 MHz has a quarter wavelength of about 31 inches, this typically requires accessing the automobiles' rod antenna, or an antenna directed through the front or rear window in order to obtain acceptable length.
Accessing this antenna typically requires a rewiring of the car, first disconnecting the antenna and then wiring the radio and navigation system to share the antenna. As navigation systems presently are installed primarily in newer and more expensive cars, people may be reluctant to have the internal wiring redone by an outside vendor. Further, such rewiring can void the warranty on the radio and/or wiring system, and can be somewhat expensive. Some manufacturers use proprietary devices, such as amplifiers and amplifier systems, which may not function properly after such an installation. Further still, sharing the antenna can result in a reduction in quality of the existing radio, as the shared antenna typically introduces additional noise into the FM signal input to the radio.
Even in simple FM radios or other FM-frequency devices, it is common to require a quarter-wave antenna. In automobiles, these antennas are subject to breakage and can be somewhat unsightly. The antennas can be included in the glass or other areas or devices of the vehicles, but this increases the cost and complexity of these parts. In handheld FM radios, the earphone wires often are used as the antenna, which has not proven to provide optimal reception. Further, portable radios often require an extendable antenna, which may not be practical for systems places in areas with minimal space, such as a bookshelf or cabinet.
It therefore is desirable to obtain a method of receiving FM signals that does not require a large quarter-wave antenna, and that allows separate devices to easily include their own antennas without the need to share a large antenna.